NiSi Circular UV Filters are made of high definition Optical Glass, feature double-sided Nano Coating technology, have a super-thin frame and offer very high transmittance. Our range features three ring types, Our highest qualityUV filter featuring a Titanium ring (Ti UV) with a Transmittance of 99.4%, Brass (HUC UV) with a Transmittance of 99.2% and our most affordable UV filter the Aluminium (SMC UV) with a transmittance of 98.9%. UV Filters block ultraviolet light and provide protection for lenses.